This invention relates to filtering devices provided with a disposable filtering element. In such filtering devices the filtering element has to be replaced periodically so as to keep the filtering device functioning properly. A micro circuit or chip integrated in the filtering element may contain unique information about the type of filtering element, the time it was installed etc. and thus enables to check whether the correct (type of) filtering element has been placed and for how long it has been functioning.
U.S. Pat. No. 5,674,381 discloses an assembly of a filtering apparatus and a replaceable filtering element, with which an electronic identification label is included in the replaceable filtering element for cooperation with read out means included in the apparatus. The well-known filtering element is in the form of a bag and the identification label is placed in a central position in (or on) the bottom part of the filtering bag for exchanging information with the read out means that is placed in the axis of the filtering apparatus. For the well-known filtering device it is thus essential that the replaceable filtering element comprises a bottom portion which carries the identification label in a central position.
In various types of filtering devices, however, open ended cylindrical filtering elements are used, with which it would not be possible to apply the electronic identification system in the way disclosed in the US patent mentioned hereinabove.
Accordingly the present invention aims at providing a filtering device of the type in which use is made of a disposable open ended cylindrical filtering element and with which electronic means on the permanent part of the filtering device and on the displosable filtering element respectively work together to enable to check whether the correct type of filtering element is placed, when it was placed, whether or when it should be replaced etc.
According to the invention this aim is achieved by providing a filtering device, more particularly a fluid filter, comprising
a casing with an inlet space for liquid to be filtered and an outlet space for filtered liquid;
a substantially cylindrical filtering element of the disposable type, which is removably placed within the casing to function therein as a liquid permeable partition between the inlet space and the outlet space;
a unique information containing micro circuit provided in said filtering element, adapted to function as an identification label and to that end cooperating with a receiver means provided in the casing, so as to provide for a periodical or continuous exchange of information between the micro circuit and the receiver means;
wherein said micro circuit is embedded, at a circumferential location, in an annular sealing means that is applied to the terminal edge of an open end of the cylindrical filtering element to provide sealing engagement between the filtering element and a corresponding seat between said inlet space and said outlet space and wherein said receiver means is provided in said seat and comprises a flat annular coil, the average diameter of which corresponds with that of said annular sealing means.
Thus unlike the filtering element in the well-known filtering device the filtering element in the filtering device of the present invention has its identification label at a location that is eccentrical to the axis of the filtering element. In spite of the latter the filtering element of the present invention may be simply put in place, i.e. without paying attention to the angular position of the label, because the annular form of the receiver means guarantees that the micro circuit will always get in an operative position relative to the receiver means.
As the micro circuit is making part of the filtering element and will thus be disposed together with the filter element after use, it is important that the circuit is designed as simple and cheap as possible. To this end a micro circuit of thexe2x80x9cpassivexe2x80x9d type is to be preferred, which may, in the manner of a transponder, cooperate with the receiving element within the casing of the filter.
However, a micro circuit of thexe2x80x9cactivexe2x80x9d type, i.e. equipped with an independent power source, may also be advantageous. The end of the life of the power source may e.g. be an indication for the time, during which the filter element has been in use. Furthermore an active micro circuit could perform certain measurings such as pressure and temperature measurings.
The invention will be hereinafter further explained by way of example with reference to the accompanying drawing.